Deakin scientists watch tagged turtles from space

16 July 2014

Photograph courtesy of R.D Kirkby and B.S Kirkby

Millions of kilometres of protected marine parks covering vast tracts
of ocean may not be enough to save some of the world's migrating sea
life.

Unique research by Deakin University scientists using satellite
tracking to monitor tagged green turtles has found the turtles move in
and out of enormous protected marine conservation zones, exposing them
to danger as they migrate from their breeding grounds to forage for
food.

The findings indicate that even the largest Marine Protection Areas
(MPAs) – some covering hundreds of thousands of square kilometres of sea
– may need to be buttressed with smaller networks of protected areas,
according to Deakin University Chair of Marine Science Professor Graeme
Hays.

An international team from Deakin University's Centre for Integrative
Ecology (CIE), Swansea University (UK) and the Seychelles located green
turtles nesting ashore at night and fitted them with satellite tags.

They then used satellites to monitor the turtles moving from their
breeding grounds in the Chagos Archipelago in the Indian Ocean, one of
the largest protected marine parks in the world covering 640,000 km2 and
renowned for its pristine coral reefs and schools of endangered
species.

"Over the last few years, governments around the world have declared
some massive marine parks, typically around ocean islands,'' Professor
Hays said. "How well these protect marine life has been heavily
debated."

The research results revealed some extraordinary data, including an
epic voyage of 3979km by one turtle, the longest published migration of
an adult ever recorded. Tracking also recorded two swimming more than
3800km westwards to the coast of Somalia on mainland Africa while
another headed 1000km north to the Maldives.

The data also revealed that seven out of eight of the tracked turtles swam more than 1000km outside the protected zones.

"In addition to protecting coral reefs and other important habitats
and species, it will also protect turtles during key periods of their
lives such as when they are nesting and when the eggs are incubating."

But Professor Hays said international cooperation is needed to
develop an additional network of smaller, preserved areas across the
Indian Ocean to protect the turtles at other times in their lives.

The report findings, titled "Use of long-distance migration patterns
of an endangered species to inform conservation planning for the world's
largest marine protection area", is published in Conservation Biology this week.

Green sea turtles are vegetarian, feeding on algae and kelp. They can
grow 1.5m in length, weigh around 300kg and live for up to 80 years.
They are found in tropical and subtropical waters, predominately in the
Atlantic and Pacific oceans.

Endangered, the turtles are hunted legally and illegally for human
consumption or fall victim to fishery bycatch or boat collision as they
move through the seas.

Professor Hays said the joint, international research revealed
migrating marine life demonstrated different types of long distance
movement, with turtles often shuttling between small breeding grounds
and foraging areas compared with fish that range more broadly.

He believes the results of the study could also apply to endangered and commercially exploited fish, such as sharks and tuna.

Marine Protection Areas (MPAs) cover vast tracts of ocean, spreading
from small plots of a few hundred kilometres to vast areas canvassing
more than 100,000 square kilometres. The Chagos Archipelago is among one
of the world's largest MPAs. Another 360,000 square kilometres around
the Hawaiian Islands is also protected.

"This massive MPA is of value for green turtles, particularly as it
protects them throughout the breeding season. But our work shows that
even massive MPAs need to be supplemented with networks of smaller
protected areas."

Covered with an anti-fouling paint used on boats, some of the tags
survived for more than a year, with one still active 15 months later.

Professor Hays said MPAs were large areas, hundreds of thousands of
square kilometres, set up by governments around the world over the last
decade as part of a global effort to reduce ocean biodiversity declines.

"Yet the effectiveness of these protected areas is often not known particularly for migratory species.

"We hope that these results will now feed in to international
conservation planning that is underway in the Indian Ocean and other
ocean basins."